AfterShip - AfterShip is the shipment tracking API for ecommerce businesses and marketplaces.

Bananatag - Find out what happens to your emails after you press send! Add email tracking, attachment tracking, email scheduling and templates to your daily emails.

Cabubble - Taxi and minicab quotes for London, Birmingham, Manchester and throughout the UK. Book a licensed taxi or minicab online via website or mobile app.

GetNotify - GetNotify is a free email tracking software solution.

OnTime 360 - Cloud-based courier software with online order entry, route optimization, and dynamic tracking. The complete delivery software solution.

Mailtrack.io - The best email tracking solution I've found. Free